Electric circuit interrupter



Dec. 13, 1938. J. BIERMANNS ET AL 2,140,378

ELECTRIC CIRCUIT INTERRUPTER Fild Nov. 24, 1936 In ventors:

Josef Bierm an 'ws,

Otto Magr,

b9 MMZM Attorneg.

UNITED STATES PATENT. OFFlCE ELECTRIC CIRCUIT INTERRUPTER Josef Biermanns, Berlin-Johannisthal, and Otto Mayr, Berlin-Karlshorst, Germany, assignors to General Electric Company, a corporation of New York Application November 24, 1936, Serial No. 112,568 In Germany December 5, 1935 6 Claims. (01. 200-147) This invention relates to electric circuit interfected when this condition obtains since the rate rupters, more particularly to the type wherein of generation of gas for extinguishing the arc is automatic generation of an arc extinguishing decreased as the distance between the are and the medium takes place in accordance with the circuit surroundingchamber walls is increased.

opening operation. In order to avoid the disadvantages referred to The principal object of the invention is the proin this type of switch, there is provided in adcordvision of an improved circuit interrupter of the ance with the present invention, electromagnetic aforesaid type which is efficient and reliable in means for acting upon and moving the are within operation, durable in construction and designed the arc chamber with respect tothe insulating l0 so as to provide an adequate amount of arc exwalls. The magnetic field in moving the are not 10 tinguishing fluid during the circuit opening only equalizes the deterioration due to gas emisoperation. sion at the insulating walls and sets up a turbulent Our invention will be more fully set forth in condition in the arc path tending to interrupt the the following description referring to the accomare but also effects lengthening of the are so that panying drawing, and the features of novelty the effective contact between the arc and the gas 15 which characterize our invention will be pointed emitting walls is increased. In addition, the out with particularity in the claims annexed to movement of the arc lengthens the life of the and forming apart of this specification. contacts due to equalizing of the burning effect Referring to the drawing, Fig. 1 is an elevaof the arc.

tional view, partly in section, of an electric cir- Referring again to Fig. 1, the electromagnetic 20 cult interrupter embodying the present invention, means for producing the field acting on the'arc and Fig. 2 illustrates a modified form of the concomprises a coil 6 which surrounds the arc chamtact structure shown in Fig. 1. ber in generally concentric relation thereto and The circuit interrupter illustrated by Fig. 1 is suitably housed within part of the insulating comprises relatively movable contact structure instructure 4. As shown the coil when energized 25 eluding a fixed segmental type contact I and a produces a radial field as indicated by the flux coacting movable tubular contact 2 operable withlines 1 within the arc chamber tending to rotate in a. restricted or closely confining arc chamber 3. the arc and cause it to assume a generally spiral The are chamber in the present case is of annular or helical shape.

sleeve-like form and is defined by insulating The coil is energized in accordance with the 30 structure comprising a main cylindrical portion 4 circuit opening movement through an arcing conand a spaced concentrically arranged central pin tact 8 which is formed as a ring through which 5 which is in registry with thebore of the tubular the contact 2 is operable. The arcing contact is contact so as to guide the same. spaced above the fixed contact I so as to be inter- In switches of this type it has been proposed mediate the fixed and movable contacts in the 35 that the insulating walls of the annular are open circuit position as shown. One terminal of chamber be composed of a material, such as fiber the coil at 9 is electrically connected to a conducfor example, adapted to emit gas when acted upon tor ID to the fixed contact terminal H, and the by the arc during separation of the contacts for other coil terminal at I2 is suitably connected to the purpose of extinguishing the are. In such the arcing contact 8. 40 switches there is the possibility that the switch Accordingly, when the contact 2 is raised to may be inaccurately assembled with respect to open the 'line circuit indicated at L the arc is alinement for example with the result that the transferred from the fixed contact I to the arcing are upon opening of the circuit has a tendency contact 8 and the coil, which is now in series with to act on but a limited portion of the arc chamthe arc is energized to project a magnetic field 4 her walls nearest the arc. This not only results into the arc chamber. As the arc is lengthened in excessive deterioration of the arc chamber at between the arcing contact 8 and the tubular consuch portions but also may result in limited gentact 2, the radial field tends to spin or rotate the eration of gas for interrupting the are. Such unare rapidly within the annular arc chamber so equal deterioration of the arc chamber walls that the arc tends to assume a helical elongated 50 necessarily results in premature overhauling of path about the central insulating pin 5. This the switch and changing of parts, particularly in action tends to increase the effective contact area the case where the arc tends to cut deep grooves between the arc and the gas emitting walls with in certain sections of the chamber walls. The the result that an effective gas blast is obtained operation of the switch is likewise adversely 91- from the arc chamber when the contact 2 is 55 withdrawn. While the contact 2 is still within the arc chamber the gas is generated at increasing pressure which by itself tends to interrupt the agitated arc.

For the purpose of concentrating the magnetic field produced by the coil 6 at a limited or predetermined section of the are generally designated'at [3, there is provided a short-circuited conducting ring I 4 which surrounds the arc chamber and is generally concentrically positioned with respect thereto. The ring 14 is spaced from the coil 6 and is adjacent the arcing contact 8 so that the coil flux is confined to a path between the ring l4 and the coil 6. Accordingly, the magnetic field is concentrated on the are adjacent the arcing contact 8, the application of a. strong magnetic field at this base point being particularly effective.

It will be apparent that under certain conditions it may be desirable to combine the arcing contact 8 and the short-circuited ring l4 as a single member.

In order to suppress leakage flux at the upper part of the coil and to concentrate the magnetic field within the arc chamber at that point, there is also provided a second short-circuited ring i5 above the coil. The rings l4 and I5 may be composed of a suitable conducting metal such as copper.

It shall be understood that the arc interrupting principle above described is not limited to the use of a single electromagnetic means as illustrated. For example, the circuit interrupter may comprise a multiple arrangement wherein the arc is drawn through an arc chamber and is subjected successively to a plurality of magnetic fields. In this case the coils would be successively cut in the circuit as the movable contact assumed a position adjacent the corresponding arcing contact.

Fig. 2 illustrates a modified form of the movable contact rod for producing a magnetic disturbance within the arc chamber upon opening of the circuit tending to move the arc with respect to the insulating walls. For this purpose, the tubular contact 2 is notched or grooved as indicated at l6 so that at the contact end the current is divided into a plurality of conducting paths indicated at l1. The grooves assume a generally spiral form for accentuating the magnetic effect above referred to.

Since the application of the magnetic field on the arc is particularly effective at one or both bases or roots of the arc, it will be apparent that the arc base at the movable contact is subjected to a magnetic field throughout its range of opening movement between the arcing ring 8 and the upper short-circuited ring l5. As above pointed out the are also passes through a concentrated field between the coil and the short-circuited ring [5. The lower base of the are at the arcing contact 8 is, of course, constantly subjected to a strong magnetic field throughout the circuit opening operation.

It shall be understood that the arrangement shown in Fig. 2 may, if desired, be used in combination with the arrangement shown in Fig. 1, or it may be used independently.

It should be understood that our invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of our invention.

What we claim as new and desire to secure by Letters Patent of the United States, is:

1. An electric circuit interrupter comprising relatively movable contacts, insulating structure defining an arc chamber within which said contacts are separable, a short circuited conducting ringv having a resistance comparable with that of copper surrounding said chamber at a predetermined point along the arc path and electromagnetic means disposed adjacent said chamber and magnetically related to said short circuited ring so that the magnetic field produced by said electromagnetic means is concentrated on a limited section of said are within said chamber.

2. An electric circuit interrupter comprising a fixed contact, a coacting movable rod contact, insulating means forming a restricted arc chamber for said contacts, an arcing contact spaced with respect to said fixed contact so as to be intermediate said fixed and rod contacts in the open circuit position, a coil surrounding said are chamber, the terminals of said coil being connected respectively to said fixed and arc contacts so that said coil is energized in accordance with the circuit opening operation and a short-circuited conducting ring having a resistance comparable with that of copper surrounding said are chamber and spaced with respect to said coil so that the magnetic field produced by said coil is concentrated on the are at said arcing contact.

3. An electric circuit interrupter comprising a fixed contact, a coacting movable rod contact, insulating means forming an annular arc chamber for said contacts comprising a centrally disposed insulating pin and spaced concentrically arranged wall structure forming with said pin a sleeve-like annular arc chamber, an arcing contact spaced from said fixed contact so as to be intermediate said fixed and rod contacts in lthe open circuit position, a coil surrounding said annular arc chamber, the terminals of said coil being connected respectively to said fixed and arcing contacts so that said coil is energized in accordance with the circuit opening operation, and a short circuited conducting ring surrounding said are chamber and disposed with respect to said coil and arcing contact so that the magnetic field produced by said coil is concentrated on that portion of the are between said arcing contact and rod contact.

4. An electric circuit interrupter comprising insulating structure forming a restricted arc chamber, relatively movable'contacts including a rod contact separable within said chamber, the walls of said are chamber being adapted to emit gas when acted upon by the arc formed between said contacts upon opening of the circuit, said rod contact at its contact endjorming conducting paths in parallel for causing a magnetic field at said contact end tending to move the are upon opening of the circuit with respect to said gas emitting walls.

5. An electric circuit interrupter comprising insulating structure forming a restricted arc chamber, relatively movable contacts including a hollow rod contact separable within said chamber, the inner walls of said arc chamber being adapted to emit gas when acted upon by the arc formed between said contacts upon opening of the circuit, said hollow rod contact at its contact end having generally spiral-shaped slots for causing a magnetic field at said contact end within said chamber tending to move the are upon opening the circuit with respect to said gas emitting walls.

6. An electric' circuit interrupter comprising relatively movable contacts, an arcing contact spaced with respect to one of said contacts so as to be intermediate said relatively movable contacts in the open circuit position, electromagnetic means associated with said arcing contact for projecting a magnetic field across the arc upon opening of the circuit and coacting magnetic means for establishing a modifying flux for concentrating said magnetic field upon that portion of the are between said arcing contact and one of said relatively movable contacts.

JOSEF BIERMANNS. OTTO MAYR. 

